1. Field of the Invention
The present invention relates generally to an adjustable apparatus for use in cleaning and polishing roll assemblies used in the rolling of sheet stock such as, for example, sheet steel, sheet plastic, paper, and the like. More particularly, the invention relates to an apparatus that incorporates a tandem pneumatic/hydraulic reciprocating cylinder with an integral oil reservoir in its design.
2. Description of the Prior Art
In my U.S. Pat. No. 4,841,675, issued on Jun. 27, 1989, I disclosed an apparatus for cleaning and polishing roll assemblies. According to this patent, a pneumatic cylinder causes reciprocating movement of the first end unit of the apparatus and a separate hydraulic cylinder associated with the second end unit dampens that movement. The two end units of the apparatus disclosed in this patent independently support the pneumatic and hydraulic cylinders, as well as the main shaft, and associated polishing surfaces, of the apparatus.
When the pneumatic cylinder of Pat. No. 4,841,675 is actuated during the operation of the apparatus, it is conceivable that undesirable stresses may be introduced into the assembly thereby giving rise to the possibility of early failure, binding in the apparatus, and excessive deflection in the main shaft.
In my U.S. Pat. No. 4,887,329, issued on Dec. 19, 1989, I disclosed a tandem arrangement of the pneumatic and hydraulic cylinders having a through rod. Tandem arrangements such as there disclosed have the beneficial effect of reducing undesirable stresses. However, in such tandem arrangements, air bubbles may develop in the hydraulic cylinder, for example, if an operator does not completely fill the hydraulic side of the tandem cylinder with hydraulic oil. Such air bubbles have the potential of causing the hydraulic cylinder to operate in an erratic or jerky motion. Operation in a jerky motion may be undesirable because an impact load would be put on the assembly and could result in an inconsistent wear pattern on the roll being polished.
Another problem in such tandem arrangements might occur due to thermal expansion. In order to adjust the speed of the reciprocating movement of the tandem cylinder, flow control valves restrict the oil flow from one port to the next. When the oil flow is restricted, heat could be generated due to friction. Such frictional heat may be transferred to the oil, resulting in an elevation of the oil's temperature, thereby possibly causing the oil body to expand. Because the oil cavity of the hydraulic cylinder is initially filled with oil, the expanding volume of oil could thus cause seal failure, allowing the oil to escape. Oil leakage is undesirable because air bubbles would then be able to enter the oil chamber and cause the jerky motion described above. Additionally, seal failure could cause the oil to continue to leak out of the oil chamber until the oil reached a very low level and the tandem cylinder assembly would fail.
With this general discussion of the problems associated with roll polishing and cleaning apparatuses in mind, it is a nonlimiting object of the present invention to provide an apparatus for cleaning and polishing roll assemblies which improves the performance of such apparatuses.
Another nonlimiting object of the invention is to eliminate air bubbles from the hydraulic cylinder of the apparatus, resulting in a smooth operation of the apparatus while cleaning and polishing the roll assemblies.
Yet a further nonlimiting object of the present invention is to eliminate thermal expansion which may result in seal leakage of oil from the hydraulic cylinder.
These nonlimiting described objects and the other objects and advantages of the present invention will become apparent to those skilled in the art with reference to the foregoing, the attached drawings, and the description of the invention which hereinafter follows.